The present invention relates to power generating systems. More specifically, the present invention relates to parallel operation of multiple electrical power generators.
The United States Electric Power Research Institute (EPRI), which is the uniform research facility for domestic electric utilities, predicts that up to 40% of all new electric power generation could be provided by distributed generators by the year 2006. In many parts of the world, the lack of electric infrastructure (transmission and distribution lines) will greatly expedite the commercialization of distributed generation technologies since central plants not only cost more per kilowatt, but also must have expensive infrastructure installed to deliver electricity to consumers.
Small, multi-fuel, modular distributed microturbine generators could help alleviate current afternoon "brownouts" and "blackouts" prevalent in many parts of the world. A simple, single moving part concept would allow for low technical skill maintenance, and low overall cost would allow for wide spread purchase in those parts of the world where capital is sparse. In addition, given the United States emphasis on electric deregulation and the world trend in this direction, consumers of electricity would have not only the right to choose the correct method of electric service but also the right to choose a cost effective service.
A single microturbine generator, on-site at a point of use, might not be able to satisfy customer demand. However, the customer demand could be satisfied by operating multiple microturbine generators in parallel and combining their outputs. For instance, ten generators, each capable of providing a maximum of 75 kW of power, could be operated in parallel to provide 750 kW of power.
Customer demand usually varies over the course of a day. Peak power is usually demanded only for limited periods of time. During these periods of peak power demand, all of the microturbine generators could be operated in parallel, with each microturbine generator providing maximum power output. When peak power is not demanded, however, two or more microturbine generators could perform load sharing to satisfy the power demand.
However, load sharing can result in inefficient utilization of the microturbine generators. Inefficient load sharing can increase the cost of electricity. Conversely, efficient load sharing can reduce the cost of electricity.
There is a need for efficient load-sharing when peak power is not demanded.